Mineralogy and Origin of the Manganese Deposit in the Sulaimani Province, Kurdistan Region of Iraq: Insight to Serpentinization-Induced Manganese Production Scenario

Abstract


Introduction
The transition metal manganese is the 12 th most prevalent element in the Earth's crust.Although the average crustal rocks contain about 0.1 wt.% manganese, it is concentration varies by rock types (Dill et al., 2013).Mn 2+ is existing either as major or minor element components in different ferromagnesian minerals where it replaces to the Fe 2+ in the mineral structure (Post, 1999).Thus Fe-Mg silicate mineral alteration regards as a substantial source of Mn 2+ to oceanic water and hydrothermal fluid because of it is high solubility (Post, 1999).
As a result of the relative compatibility behavior of manganese in the magmatic system, the concentration of manganese decreases gradually from ultramafic to mafic, and finally to acidic rocks (Balta et al., 2011).A widespread distribution of sedimentary manganese in different ages and geological settings has been documented throughout the geological time scale of the Earth's crust formation (Fig. 1a) (Kuleshow, 2011;Roy, 1981).Different formations and depositional environments have been suggested, including terrestrial laterization and deposition on the bottom of the present-day oceans, shallow seas, and lakes (Polgari et al., 2012).
On the basis of geochemical data of marine manganese deposits and tectonic settings, four major genetic categories are recognized: hydrogenous, diagenetic, hydrothermal and biogenic-bacterial deposits (Oksuz, 2011;Polgari et al., 2012).Moreover, manganese deposits may also form by a combination and interaction of these processes (Jach and Dudek, 2005).The Kurdistan Region of Iraq is located within the Zagros mountain ranges, which tectonically represent the convergence zone between Arabian and Eurasian plates (Alavi, 1994;Agard et al., 2011).This orogenic belt comprise a across section of the Neo-Tethyan ocean basin represented by a typical ophiolite sequence.Metalliferous deposit including umber and pelagic deposits has been recorded in the sedimentary unit of ophiolite worldwide including Semail ophiolite (Tumiati et al., 2010).Zagros manganese and ferromanganese deposits are typically connected with fragments of the Neo-Tethyan oceanic crust, including radiolarian cherts and basaltic rocks that form the ophiolite sequence's top (Zarasvandi, 2016).
The Kurdistan region has a lot of mineralization, some of these are situated in carbonate facies.Lead-zinc deposits are located in the upper cretaceous carbonates (Awadh et al., 2008, Awadh andNejbert, 2016), and the other are within igneous rocks in northeastern Sulaymaniyah (Awadh, 2019).Several ore types of mineralization represented by iron deposited was located in Garago Formation in Duhuk that was deposited in an open platform (shelf lagoon) and a restricted platform (Mirza et al., 2016).The top pelagic sedimentary facies of the Neo-Tethyan oceanic basin extended from the south in Oman, passed by Kermanshah western Iran, to Qulqula, Kurdistan region of Iraq and ended with Kocali basin to North in Turkey (Fig. 1b) (Berberian and King 1981;Ali et al. 2013;Baziany,2014).Numerous numbers of economic and striking manganese and or ferromanganese deposits recorded in Oman (AI Hammah Range -Wahrah Formation), Iran (Nasirabad and Abadeh, Gugher and Gushk, Tashk, Sorkhvand and Kamyaran deposits), Turkey Emir deposit (Sorgun-Yozgat deposit), Greece (Andros) and Cyprus (Troodos Massif) (Kickmaier and Peters, 1990;Ӧztürk,1997;Maghfouri et al., 2019).Volcanic-sedimentary manganese occurrences related to the Qulqula radiolarite near Penjween, Kurdistan Region of Iraq has been recorded in Iraq (Sissakian, 2018;Jassim et al.,2021).However, manganese deposits associated with Neo-Tethyan ophiolite unit in the Kurdistan region of the Zagros orogeny have not been pinpointed in the published literatures.
Therefore, the present paper provides the first attempt to identify the detailed locality occurrence, mineralogical investigations, geological settings of manganese deposits.Moreover, a new proposal suggested the process in control for the manganese deposit formation in the Kurdistan Region of Iraq that associated with a typical top pelagic layer of ophiolites.The minerals association and assemblage of manganese deposit in Kani Saif, Kani Manga and the Mawat area were identified.The antiquity of the sedimentary environment, and elements that control of Mn mineralization in Qulqula were explained.This study based on field observations and description, reflected light microscopy and X-ray diffraction.

Regional Geology
The Mn deposit bearing sedimentary facies is almost associated with deep marine radiolarite chert of Jurassic to the Cretaceous period within the Neo-Tethyan oceanic basin, forming the top sedimentary parts of Zagros ophiolite belts which is intern integral parts of the Zagros Orogenic belt (Mohammad et al., 2014).The Zagros orogenic belts are tectonic response of prolonged cretaceous to the Paleogene subduction collision cycle between Arabian and Eurasian plates (Mohammad and Cornell, 2017).These plates amalgamation leading to coexist different geological and tectonic units treading NW-SE ranging from Precambrian to Paleogene (Koshnaw et al.,2021).In the frame of the regional tectonic anatomy of Zagros orogenic belt (Gürbüz and Farzipour Saein, 2019), Zagros orogenic belt in the Kurdistan region of Iraq encompass three parallel NW-SE-trending tectonic units.These are (1) the Sanandaj-Sirjan zone, (2) the Imbricate zone, and (3) the Zagros fold and thrust belt (Mohammad et al., 2014;Le Garzic et al., 2019).The 40 Km wide Sanandaj-Sirjan Zone (SaSZ) in the Kurdistan Region of Iraq occupying an area of about 700 ̴ 800Km2.It is representing the complete narrow V-shaped salient into adjacent Iranian territory.It consists of deformed and metamorphosed phyllite interbedded with meta carbonate, with some restricted occurrences of different types of igneous rock along the border line with Iran and terminated by 95 Ma Penjween ophiolite from the south (Mohammad et al.,2021).The Sanandaj-Sirjan Zone is of Eurasian affinity which was merged to the north east Arabian margin by the end of Neo-Tethys ocean closure during Late Eocene (Berberian and King, 1981;Mohajjel et al., 2003).The SSZ followed by Imbricated Zone with the Main Zagros Thrust Fault that separates theses tectonic units in the area.The narrow-Imbricated Zone of about 12-25 Km thick extended parallel to the main Zagros mountain belts trend.In the Kurdistan region of Iraq, it is extended 150 to 160 Km from Byara in the south east to Qladezah in the northwest.The main geological units exist are Qulqula radiolarite, Avroman Formation, Mawat ophiolite, Bulfat Igneous complex, and cretaceous-Paleogene volcano sedimentary units and intermountain basin sedimentary Formations (Mohammad et al., 2014).
The Zagros Fold and Thrust Belt, The ZFTB is divided into High Fold And Low Fold belt on the basis of folds wavelength and amplitude, with the fold amplitude decreasing toward the Mesopotamian basin.It is represented by 12-13 Km thick of deformed sedimentary cover ranging from Cambrian to Quaternary (James and Wynd, 1965;Motiei, 1993;Alavi, 2007).The folds are well-developed (Falcon, 1974;Colman-Sadd, 1978).including the hydrocarbon-prolific Kirkuk embayment (Dunnington, 1968).The oldest rock unites represented by the Precambrain Khabour Quartzite Formation, while the youngest is the Quaternary conglomerate of the Bakhtyari Formation.Southwest of the Low Fold and Thrust belt is Mesopotamian which it is the distal part of the foreland basin.That is characterized by buried anticlines that run northwest-southeast, including the hydrocarbon-rich Mesopotamian embayment (Dunnington, 1968).

Local Geology and Field Descriptions
From the northeast to the southwest the following geological units crop outs in the area (Figs.1C  and 2)

Penjween Ophiolite
95 Ma Pejnween ophiolite occurs as elongated slices of Neo-Tethys oceanic crust covering of about 42 Km 2 of Sanandaj-Sirjan Zone in the Kurdistan Region of Iraq, thrusted over Qulqla radiolarite in the Imbricated zone along the main Zagros thrust fault (Mohammad et al., 2021).It is extended about 15Km parallel to the main trend of the Zagros mountain belt with NE-SW structural trends.U-Pb geochronology and geochemical data of various rock units of Penjween ophiolite (PO) suggested that it is belong to the outer ophiolite belts of the main Zagros ophiolite belt (Mohammad et al., 2021).PO is bounded from the east by Gimo-Qandil Group and from the west by Qulqula radiolarite (Fig. 1c).The Penjween ophiolite consists of about 300 m thick mantle sequences mostly serpentinized harzburgite with some restricted dunite, pyroxenite veins and chromite pods to the southwest, occupying the summit of Mlakawa mountain, to the west followed by about 2 Km crustal sequences represent by various types of gabbro's (Ali and Rostum, 2021), dykes of diorite and volcanic rocks at the Mlakawa mountain slope and base respectively (Mohammad, 2011;Mohammad et al., 2021).Within the volcanic units occasionally bolder of metalliferous recrystallized quartz dominated rock occurs north of the Kani Manga village.As a result of the intense deformation, squeezing and extensive thrusting a combined obduction-collision events in the area from Upper Cretaceous to the Late Eocene (Mohammad et al., 2021), is obvious that the stratigraphy sequence of the Penjween ophiolite complex apparently overturned (Fig. 2) (Ali and Rostum, 2021).

Qulqula Radiolarite
Late Triassic -Early Late Cretaceous Qulqula Radiolarite (QR) composed of numerous longranging marine deposits of intensively deformed neritic limestone, debrites and turbidities, hemiturbidite, hemipelagite, pelagic limestone and radiolarite and red claystone from oldest to youngest (Baziany, 2014;Al-Qayim et al., 2018).It is deposited on the juvenile oceanic crust of the Neo-Tethys oceanic basin which is now considered as Zagros ophiolite belt.In some area the Qulqula radiolarite intruded by small basaltic igneous rock.Underline, the Penjween ophiolite to the west, the first unit of Qulaqla Radiolarite exposed near the Kani Saif village which is represented by metalliferous rocks which is mostly resemble to be the umber unit of well-developed ophiolite.Umber near Kani Saif village, is Jasper like reddish-brown metalliferous claystone rock, intensely deformed and crushed up to 200 meters thick, highly jointed and locally brecciated, with some occurrences of veins filling manages ores and hydrothermal vein filling quartz.Laterally to the southwest the umber zone passes into thinmedium bedded radiolarian chert of about 300 m thick.The dark chocolate and red brown cherts accompany syngenetic manganese minerals in the forms of dense disseminated thin black bands with an average thickness of 1 to 2 cm.Local segregations of micro manganese nodule exist intercalating manganese thin beds within the radiolarite chert.The Qulqula Radiolarite in the area unconformably overlaid by the Oilgo-Miocene rock unit.The chert with dark banded radiolarian-bearing mudstone characterized by true pelagic and radiolarite facies of radiolarian wackestone-packstone microfacies, Radiolaria-rich ribbon chert, chert-shale couple, siliceous limestone (Baziany,2014)

The Intermontane Molasse Basin (Merga Red Beds Group)
After the development of the proto-Zagros fold-thrust belt between the Arabian and Iranian plate, along the main Zagros thrust fault weak zone, a nonmarine river channel deposit has been deposited represented by Oligocene Merge Red Bed Group.Jassim et al. (2006) divided Mega Red Beds into lower and Upper Merga Units.The Merga I unit (Lower Merga Beds) consists of red calcareous silty shales, interbedded with gritty, and locally pebbly, sandstones, which occasionally pass into conglomerates.The overlying Merga II unit consists of massive conglomerates composed of pebbles and boulders of manganese, chert, ophiolitic metamorphic and igneous rocks derived from the east and west flanks of the paleo river channel represented by ophiolite and Qulqula radiolarite respectively.The Merga Group is up to 500m thick.The Merga I unit has variable thickness and locally disappeared along the Imbricated zone; Merga II is usually 200-250 m thick.Koshnaw et al. (2021) confirmed the existence of Merag Red bed group around Mawat district.North to the Mawat district numerous numbers of exotic boulders of manganese ore have been recently observed associated probably with the Merga unit, varying in size from 10 cm to 2 m.They are very hard massive blocky with deep black color.

4.Samples and Analytical Methods
Forty-five samples of manganese bearing and host rock samples covering nearly complete occurrences of manganese distribution in Sulaimani metallogenic, Kurdistan Region of Iraq were collected at two main outcrops.Thirty-five samples from the Tapa Sura area (35˚ 29ˈ 58.22̎ N, 45 ˚ 57ˈ 57.03̎ E) and ten samples from 1km north of the Mawat district (35˚ 54ˈ 26.22̎ N, 45 ˚ 23ˈ 54.99 E) were collected during March 2021 and June 2021.Samples distributions are shown on Figs.1b and 1c.Fifteen thin sections and fifteen polished thin sections were prepared from different samples on the basis of the mode of occurrences of manganese minerals and lithostratigraphic distribution.Laboratory-based investigations involved routine polarized transmitted-incident optical microscopy supported by Scanning Electron Microscope (SEM) and X-ray diffraction studies.Microscopic examinations and XRD analysis are done at Geology Department, Sulaimani University, Kurdistan Region of Iraq.Thirteen manganese phase bearing samples were selected for XRD analysis to identify most dominated minerals present in the manganese bearing rocks and bulk-rock samples.XRD performed on Malvern Panalytical X-Ray Diffractometer (XPERT-PRO diffractometer) instrument with analytical conditions Cu-Kα1 (Å): 1.540598 radiation; 45 kV/40 mA power supply, Scan axis: gonio; angle: 10.00° -80.00° and Counting time: 1.00 second.The obtained diffractograms were analyzed using High Score Plus software and the ICDD database.The high resolution combined secondary and back scattered electron images for three polished sections obtained from FEI, Inspection F50 FE-SEM at ALKHORA SEM LAB, Baghdad, Iraq equipped with the Everhart-Thornley detector (ETD).Operation are conditions set at 20-30 Kv with viable working distance.

Ore Structure and Textural Features
Manganese ore-bearing rock units are restricted to the area between the ophiolite dominated zone and the epi-ophiolitic radiolarite unit of the Ququla Radiolarite.The recently investigated manganese deposit are located 98 kilometers north east and 64 km north from the Sulaiman respectively.Manganese in Sulaimani metallogenic province can be subdivided into two main groups on the basis of their relation to the host rocks and the nature of manganese deposits as follow:

Radiolarian chert-hosted manganese deposits
Radiolarian chert-hosted manganese deposits are narrow belts and laterality scattered units of the Qulqula radiolarite along the entire Imbricated Zone in the Kurdistan Region of Iraq (Fig. 1b).It is occurred in a belt that spans the entire Sulaimani metallogenic province from southeast to northeast along the collision zone.Manganese deposits of the epi-ophiolitic rock are associated with Umber, radiolarian chert, siliceous shale, brown claystone and a basalt succession in Mlakawa -Tapa sura area.The chert sequences in the area generally represent mid oceanic ridge proximal bedded facies of the Qulqula radiolarite which were deposited during Middle Jurassic-Early Cretaceous in the Neo-Tethys oceanic basin (Baziany, 2014).Generally, the bulk of manganese mineralization are spatially related to reddish brown radiolarian cherts that overlie the volcanic unit of the Penjween ophiolite during the deposition (Figs.3a and 3b).In the vicinity of the Penjween ophiolite, first occurrence of proximal Fe2+rich Mn2+-poor mineralized patches observed which is represented by patched of jasperite recorded in the basaltic unit of Penjween ophiolite north to Kani Manga village (Figs.3c and 3d).Jasperite is dark red hematite-quartz dominated rock with minor pyrite and chalcopyrite.Field investigation reveal the coexistence of various ore structures associated with radiolarian cherts including syngenetic layered, brecciated, micronodular and disseminated-banded manganese mineralization 5km southwest of the Penjween ophiolite.In the megascopic view the layered types represented by proximal alternating beds of 10-15 cm thick of Fe-Mn rich pelagic sediments of deep red colors belongs to umber unit with maximum thickness of about 200m just to the southwest of Kani Saif village.Manganese layers are not pure manganese minerals, they contain variable proportions of clay minerals, Radiolaria fossils and cryptocrystalline silica.In hand specimen and thin sections, the brecciated type is composed mainly of brecciated chert and siliceous red shale with the matrix of manganese minerals filling (Fig. 4a).Vein filling, brecciated and layered manganese deposits generally restricted to the umber zone and lower parts of Qulqula radiolarite unit in the area (Figs.3e, f and g).Banded types manganese deposit consists mainly of densely disseminated cyclic nano crystalline manganese minerals alternate with mudstone and ferruginous mudstone, occasionally the dens band of manganese Nano minerals form local micro nodule of manganese deposit (Figs.4a, b and Fig. 5b).Micronodule are common features of diagenetic manganese deposit.During diagenetic modifications of the chert bearing manganese beds, the remobilization of ore minerals during deformation events have resulted in the accumulation of pyrolusite as centimeter scale nodules (Fig. 4c).Moreover, a rhythmic alternation of quartz-rich chert beds and clay-rich interbeds suggests a strong differential diagenetic modification of radiolarite chert in the area (Abrajevitch, 2020) (Fig. 4d).The distal banded types restricted to certain bed of 200 m thick and 1 km wide, within the middle parts of radiolarite unit of the Qulqula radiolarite which might be considered as stratiform types of manganese deposit in the area as it is sandwiched between manganese free cherts beds.Hydrothermal vein filling with multiple generations of agate and manganese minerals association are common in the area (Figs. 3 e and f).

Exotic blocks of Mn associated with the Merga Red bed Group
Around 30-40 blocks of variable size and shapes (Figs.6a and 6b) of epigenetic manganese dominated minerals has been recorded in a very restricted area (0.1 km 2 ) north of Mawat as scattered boulders above the Merga Red bed group.They are variable in size from 10 cm to 2m wide blocks.The dominated block size is around 1m 3 in volume.The larger blocks are segregated into black manganeserich cores (Fig. 5c) and brown iron rich margins with some quartz veins.The blocks are very dense and massive associated with the viable size blocks of ophiolite related gabbroic rocks and nummulitic limestones of the Walash-Naopurdan groups (Fig. 6a).Field criteria indicated that the blocks not related to host rock rather than it is transported either by the high energy river, or as a debris-rock slide form flanks of the Red bed river basin or by tectonic activity to the basin of Red bed.As the blocks are of irregular shapes and the area represent the huge displacement of the ophiolite units in addition to the Qulqula Radiolarite formation blocks.Thus, the Mn-rich boulders are highly possible to be sourced from the Qulqula Radiolarite that filled the intermountain basin of the Merga Red bed basin during Eocene.No syn and post sedimentary Mn rich beds or lenses recorded or observed with the Merga Red bed in the area.

Mineralogy
The polarized microscopic investigations and XRD diffractogram phase identifications confirmed that the mineralogy of manganese deposits in Sulaimani metallogenic province are relatively simple.The main manganese minerals present within the samples obtained from the radiolarite host rock is pyrolusite dominated with minor hollandite, while those associated with the Red bed are braunite and rhodonite dominated.Quartz, cryptocrystalline silica, calcite, iron oxides and clay minerals are gangue minerals.

Pyrolusite
Pyrolusite is the dominated components of layered, disseminated-banded and vein types Mn deposit in the area.It shows the high reflectance yellow color in reflected light.In vein types it is occurs as coarse to medium bladed crystalline aggregate occupying the center of the veins mantled by coliform hollandite layers (Fig. 7a), suggesting low temperature crystallization from hydrothermal Mn bearing rich fluid.In both disseminated-banded and layered types (Fig. 7b) the Mn phase consists of nanocrystalline aggregated of pyrolusite (Figs.8a, b, c and d).The dominance of pyrolusite minerals is comparable to that of typical hydrothermal epi-ophiolitic rock Mn-deposit deposits in Oman, Iran and Turkey.

Braunite
Braunite is the most dominant mineral in all studied samples from massive boulders associated with the Merga Red bed group, with a modal percentage of 70-80 % at the boulder center.It shows dull grayish white in reflected light.Occasionally very fine grain light yellow inclusions are observed in some coarse grain of braunite (Figs.7c and 7d), which is highly possible to be a pyrolusite.It is modal percentage decrease toward the boulder rim reaching around 20 %.It is occurring as euhedral to subhedral of fine to medium grain minerals.The braunite grain size increase toward the centers of the boulders.No braunite has been identified in Mn deposits associated with the Qulqula Radiolarite around the Kani Saif village.

Rhodonite
The Mn-pyroxenoid rhodonite generally occurs in metamorphic manganese-bearing deposit.It is occurring as coarse grain euhedral to subhedral (Fig. 7e) grain with modal percentage less than 10 % in the massive boulder.The occurrence of Rhodonite only restricted to massive boulders in the studied area.

Hollandite
Hollandite is only restricted to vein types shows colloidal texture along the rim of the vein.It is characterized by a yellow-grey color under reflected light.The pyrolusite-hollandite assemblage association can be observed under the microscope.

Gangue minerals
The main gangue minerals are quartz (Fig. 7f), calcite, hematite, clay minerals and microcrystalline silica, with the latter two minerals restricted to deposit associated with radiolarite chert.On the basis of the modal percentage of hematite as gangue minerals, the massive boulder deposit is divided into two remarkable different zones: outer hematite rich zone that is very low in manganese and a central manganese oxide-rich zone that is very low in iron (Fig. 10b).The thickness of the hematite zone is variable from boulders based on the size of boulders.

Mineral Paragenetic
Field observation, petrographically and XRD data (Figs.9,10 and 11) among manganese minerals are clearly indicated time relations in studied manganese deposits.Through sequences of layers in vein filling, replacement relationships among the manganese phases, recrystallization and deposition relative to the distal and proximal area of the discharging sources and subsequent metamorphism.Thus, it is evidenced from these relationships that the manganese deposit in the area may have formed through four successive stages as follow:

Hydrothermal stage
Near to the Penjween ophiolite, a paleo mid oceanic ridge fragment; hydrothermal course crystalline quartz is the predominant constituent (90 vol.%) with ample fine-grain hematite (10 vol.%) in the jasperite samples (Fig. 9a).All quartz is white and clearly pre-dates the associated Fe oxide mineralization represented by hematite.In addition, the vein filling shows evidence of multi-stages of the quartz generation of variable chemistry evidenced by the obvious color change from milky white to colorless agate (Figs.3e-g).The observed increase in density of quartz veins in the Umber zone close to basaltic unit ophiolite may have been resulting from preserving of silica-saturated, high-temperature hydrothermal solutions rising across fracture-controlled porous regions beneath a paleo mid-ocean ridge crest in the area during the cretaceous period.Close to lower parts of the Umber zone the volume percentage of quartz in the veins gradually decrease until it is completely disappeared and replaced by veins consisting of micro layers of hollandite along the wall of the vein and pyrolusite in the center (Fig. 5a).Martin and Lowell (2000) suggested that the quartz vein precipitation near to MOR crest resulting from cooling down of silica-saturated, high-temperature hydrothermal fluid through the fracture-induced permeable zone via reaction with cold oceanic water.

Nano manganese deposition
The alternate bands of the nano-pyrolusite rich band followed by the pyrolusite free band (Fig. 5b), may suggest manganese colloids precipitate on the ocean bottom sediment surfaces as nano-crystalline which is evidenced by the weak XRD intensity pattern (Fig. 10a) of pyrolusite and their Nano size in high resolution scanning electron images (Figs.8a-b) for banded types manganese ore in the area.
Mn 2+ + ½ O2 + H2O = MnO2 + 2 H + (Froelich et al., 1979) ( In general, mid-oceanic ridge related hydrothermal plumes is emitting significant elements (Fe, Mn, Ca, Si, Cu, Co, Zn, Pb, and Cd) particularly Fe and Mn to the global oceans, producing midwater enriched in metals that are transported from the source to variable distances (Tivey, 2007).Incident particle precipitation upon emission from hydrothermal solution controls elements diversity and the extent of elements transfer and redeposition along the entire oceanic basin (Tivey, 2007).The observed rhythmic pyrolusite rich band may attributed to the cyclic nature of vent activity, which intern controlled by the cyclic magmatic activity along the spreading center (Fig. 12), the Upper Cretaceous Penjween ophiolite-remnants of an anomalous mid-ocean ridge segment of the Neo-Tethys, was actively supplying metals to the Neo-Tethys oceanic basin before the obduction stage to the basin of the Qulqula Radiolarite in the studied area.The restricted occurrence of Fe-Mn metalliferous radiolarite chert from Oman, Iran, Iraq and Turkey suggest that hydrothermal plumes in the Neo-Tethys ocean was reached maximum activity during the deposition of this unit in the Cretaceous age.
Geochemically Mn 2+ is associated with Fe 2+ , as both of these elements are soluble during serpentinization and subsequently enriched in hydrothermal fluid that discharge through the plume to the ocean.In respect to redox state and mineral formation Fe 2+ is much more sensitive than Mn 2+ , thus the residence time of Fe 2+ in the neutrally buoyant plume more likely is minutes to hours (Field and Sherrell, 2000), meanwhile the residence time of Mn is prolonged for years (Mandernack and Tebo, 1993;Klevenz et al. 2011) predict low concentrations of Mn 2+ in addition to the lack of manganese oxides precipitation nearby to the discharge area as a result of prolonged oxidation kinetics of Mn 2+ (Morgan, 2005;Luther et al, 2015).
The deposition of silica and iron near the hydrothermal vent giving rise to the formation of Fe-rich Mn-depleted rock type (jasperite), while manganese as a more mobile element precipitated at a certain distance from the plume and vent where the Mn bearing fluid was diluted by seawater.The slow input rate of solution in addition to the absence of strong currents in deep down to 3000m promoted an efficient separation of Fe and Mn, resulting in the accumulation of sediments with markedly distinct Mn/Fe mineral ratios within a relatively limited area.The first level of Mn-bearing sediments represented by umber zone accumulated near a passage of hydrothermal solutions circulating in the oceanic crust and sediment interface as a result of slow thermal convection.

Diagenetic
The accumulation of manganese micronodule throughout out the pyrolusite bands and vein nets (Figs.4a-b) suggest a post depositional diagenetic mobilization of Mn as results of tectonic activity or the post depositional migration of manganese from reduced Mn bearing strata to oxidized one.To accumulate Mn into substantial deposits, manganese required to be oxidized to Mn 3+ or Mn 4+ (Calvert and Pedersen, 1996).Lynn and Bonatti (1965) suggests that manganese dissolves upon burial in reduced sediments, then slowly migrates and accumulates as nodules or micronodules in the oxidized top strata.Moreover, Araújo et al.(2021) introduced the oil-like model for accumulation through the late diagenesis process that allow manganese oxides to migrated through faults and assembled in low-strain zones and/or within the high porosity and permeability intervals in the host rock (Figs.4a-b).The accumulation of manganese micronodule in association with disseminated pyrolusite band may supports early-stage mobility and accumulation in the studied samples.released during serpentinization process is heated by exothermic reaction in addition to heat from lithospheric substrate, where it becomes buoyant and discharged to the ocean bottom through the intensive vent structure or highly fractured zone.Subsequent metal deposition and distribution occurs based on metal setting times and oxygen availability around discharge area.

Metamorphic stage
The occurrence of mineral assemblage braunite, rhodonite, quartz and calcite (Fig. 10b) in the massive types deposit in the Mawat area is the diagnostic indicator of the metamorphism.The primary pyrolusite bearing chert start to react with quartz to form a new mineral assemblage barunite and rhodonite (reactions 1 and 2).The disappearance of pyrolusite and quartz on the XRD chart in massive type ore can be use as identical evidence of metamorphic stage.Mineral reactions among manganese minerals in the area can be explained in the system SiO2-MnO-CaO-CO2-O2 as follow (Bhattacharyya et al., 1984;Cabella et al., 1991): (2) Braunite + Quartz →Rhodonite + O2 (3)

Proposed Proposal for the Mn 2+ Source
A different model is proposed as sources of Mn, including seawater, hydrothermal-exhalative, exhalative-terrigenous, lower crust/mantle, volcanic ash, and oceanic magmato-sedimentary (Chen et al., 2018).However, Mn/Fe and other metals in the studied area were regarded to have been released from ultramafic rock via serpentinization process in mid-oceanic ridge geological settings.Our proposal begins with the occurrence of protrusion of an ultramafic body of harzburgite composition through a ridge axis.We proposed that the upper mantle unit of the Penjween ophiolite have been subjected to a variable degree of the serpentinization process via infiltration deep seawater infiltrating through fractures in the oceanic crust to the reaction zone prior obduction (Mohammad, 2011;Mohammad, 2013;Mohammad and Mousa, 2009).In the reaction zone, syn serpentinization fluid rich in Fe and Mn, Ca, Mg is heated by hot mantle substrate and or exothermic serpentinization reaction where it becomes buoyant and quickly proceeds to the ocean floor to be discharged through a plumes and vent structure or infiltrating through more fractures, diluting with seawater and being discharged as diffuse hydrothermal fluid rich in Mn and Fe.Manganese is solely in divalent form in a wide range of mafic minerals where it substitutes for iron (Post, 1999).Average of about 0.1% Mn in igneous rocks (Turekian and Wedepohl, 1961).Thus, olivine, pyroxene and spinel are altered to serpentine and magnetite which provide a substantial source of Mn 2+ to hydrothermal fluid.
The serpentinization of mantle rocks in the Penjween ophiolite is a ubiquitous process as reflected by the widespread occurrence of serpentinites observed in the field near to manganese deposit in the area.Hydrothermal input of Mn and Fe through the plume into the ocean water column has been attributed to the interaction between seawater and mantle rocks is in the ridge area (e.g.Charlou et al., 1993;German et al., 1996;Bougault et al., 1998).The chemical interactions that take place of Mn released in the water through hydrothermal vent at the interface with oxidizing water via oxidation process and subsequent precipitation of nano-manganese oxides (pyrolusite) could be occurs via oxidizing reaction.
Experimental, geochemical modeling and near to vent hydrothermal geochemistry studies indicated that ultramafic-water interaction though serpentinization process is the major supply of Fe, Mn and Si, Ca to the hydrothermal fluid associated with this process (Equation 4) (e.g.McCollom, 2007;Seyfried et al., 2007;Hellevang, 2008;Klein et al., 2009;McCollom and Bach, 2009;Hellevang et al., 2011;Marcaillou et al., 2016, Alt 1995;Butterfield et al., 2004) Peridotite + H2O → serpentinite + Hydrothermal fluid with significant dissolved Fe, Ca, Mn, Zn,S and SiO2(aqu) Mineralogical and chemical data from meta harzburgite of the Penjween ophiolite indicate that the parent olivine and spinel contain up to 0.4 wt.% and 1.2 MnO respectively (Mohammad, 2011).Meanwhile up on hydrothermal alteration the products of these two minerals represented by chromium magnetite and serpentine show decreasing MnO to 0.1 and 0.25 wt.% respectively (Mohammad, 2011).Thus, suggesting significant Mn release to the hydrothermal fluid (Equation 5).
MnO (OL, PX, CS) + H2O →Mn 2+ + 2OH -(5) Most of Fe during serpentinization of olivine is accommodate within the serpentine product while the bulk of the remaining Fe 2+ is incorporated in syn-serpentinization magnetite.Later alteration of brucite and serpentine will release Fe 2+ to hydrothermal fluid (Palandri and Reed, 2004).The SiO2 released via alteration of olivine and pyroxene during the serpentinization process.Up on cooling of the hydrothermal fluid rich in aqueous SiO2 start to form quartz veins in a transition zone between hot hydrothermal upwelling and cooler seawater circulation in the shallow crust (Martin and Lowell., 2000).Palandri and Reed (2004) conducted simulation for harzburgite serpentinization processes through a series of reaction (6-9), they concluded that serpentine, hematite-magnetite, and brucite in addition to hydrothermal fluid with the considerable amount of Mg, Fe, Mn, Ca 2+ and SiO2 can formed via water/ rock reaction at 25 to 300°C and pressure 10 to 100 bars.XRD shows calcite grains dispersed in pelagic red clay (Fig. 9a) associated with Manganese poor beds, perhaps precipitated from hydrothermal fluid associated with serpentinization of diopside.It is substantial that the calcite grains were found in the Umber unit closer to the hydrothermal vent.In mid oceanic ridge conditions, when calcium-rich hydrothermal fluid mixes with seawater, calcium in the fluids combines with carbonate to precipitate aragonite and calcite (CaCO3).Mineralogical, relative ages and stratigraphic correlation of these epi-ophiolitic manganese bearing chert horizon with radiolarite facies associated with the Neo-Tethys oceanic belt spreading from Oman to Turkey which is suggest that they are of common origin and spatially related.In depth considerate of physicochemical environments of manganese deposition with the frame Neo-Tethyan ocean in the Jurassic -Early Cretaceous yield valuable information towards understanding the tectonic and evolution history of the Neo-Tethys oceanic basin from early to the mature stage.

Conclusions
The manganese deposits in the Sulaimani metallogenic province are associated mainly with the Qulqula Radiolarite in the Tapa Sura area with restricted occurrence associated with the Merga Red bed Group in the Mawat area.Different modes of occurrence of the manganese deposit in the area have been recognized including vein, brecciated, disseminated, micronodules, banded and massive types, which are of syngenetic origin.The mineralogy of manganese deposits in the area mainly consists of pyrolusite and hollandite whereas those found in Merga Red bed samples are dominated by braunite and rhodonite.Quartz, cryptocrystalline silica, calcite, iron oxides, and clay minerals are dominated gangue mineral.Time paragenetic relations among the manganese phases in the study area suggest the formation of manganese deposits in the area faced multiple succession stages which are; hydrothermal, deposition, diagenetic and metamorphism stages.This stage reflects the evolution history of the Neo-Tethys oceanic basin from the mature stage in the Cretaceous to the final closing stage in Eocene.The sources of manganese in the studied area are related to the serpentinization processes of Penjween ultramafic units' ophiolites prior to the obduction process in the mid oceanic ridge tectonic setting in Cretaceous.During the hydrothermal alteration process, Mn released from the alteration of olivine, pyroxene, spinel, and enriched in the hypothermal fluid generated.Subsequently, the Mn rich fluid discharged through plumes and vents to the Qulqula Radaiolarite basin.

Fig. 1 .
Fig. 1.(a) Global distributions of manganese deposits, including manganese deposits of Tethyan belt (modified after Maghfouri et al., 2019); (b) Distribution of manganese bearing radiolarite chert along the Zagros orogenic belt; (c) Geological map of Penjween area showing various geological units in additions to the sample's locations.

Fig. 2 .
Fig. 2. A-B geological cross section and stratigraphic column of Penjween area

Fig. 4 .Fig. 5 .
Fig. 4. Field photographs near Kani Saif village showing: (a-c) Banded and micronodule types of manganese deposits horizon within radiolarite zone, arrow indicate possible pathway of Mn mobility during diegetic process (Samples No. DY-11A and DY-11B); (d) Identical manifestation of bedded chert sequence with rhythmic alternation chert beds and) shale interbeds within the Qulqula Radiolarite

Fig. 12 .
Fig. 12. Diagram illustrating the hydrothermal structure along the MOR crest, showing cold deep seawater infiltrating through fractured weak zone into the reaction zone in the crust-upper mantle section of Neo-Tethys oceanic crust.In the reaction zone, fluid rich metals especially Fe 2+ , Mn 2+released during serpentinization process is heated by exothermic reaction in addition to heat from lithospheric substrate, where it becomes buoyant and discharged to the ocean bottom through the intensive vent structure or highly fractured zone.Subsequent metal deposition and distribution occurs based on metal setting times and oxygen availability around discharge area.